Constituencies return a set number of ‘winners’.
Usually this is in the region of 3 to 4.

A party for an election can put forward as many candidates
as it likes for a constituency as long as it does not exceed the maximum set
i.e. it can’t go above 4 for a constituency if this is the figure set.

Voters have as many votes as there are candidates and they
place their votes in order of preference.

Voters can vote for candidates from other parties and they
can decide their own order of preference.

Seats in a constituency are awarded in proportion to votes
cast, with second, third and other preferences of the voters taken into account.

Voters have huge choice under this system. It can favour
independent candidates.

STV encourages parties to select a socially varied group
of candidates in order to maximise voter preference.

STV favours small parties and independents. Therefore the
system produces governments with no overall majorities which can be unstable.
STV can create coalition governments with a dominant party dependent
on smaller parties for its survival.